Earth’s Climate: Past, Present and Future   Fall Term - OLLI West: week 2, 9/23/2014 Paul Belanger Earth's past climate history Earth’s deep past before the Cambrian (600 MaBP): hot and cold Earth’s past: Cambrian onward: mostly hot-house Earth;  100s parts per million (ppm) Climate trend in the Cenozoic – the last 65 million years; proxy data from 3600ppm to <200 ppm. More recent past: 180-280 part per million; how do we know – empirical data. Preview of next week’s field trip Today: 400 ppm and growing 2-3ppm/year

REVIEW OF WEEK 1 ITEM

Video I showed at end of week 1 class – what is climate: You tube link: https://www.youtube.com/watch?v=bjwmrg__ZVw Video I didn’t show – /don’t have time – see syllabus: The climate system, feedbacks, cycles and self-regulation 1.6 https://www.futurelearn.com/courses/climate-change-challenges-and-solutions/steps/3294/progress (7 mins) an alternate: https://www.youtube.com/watch?v=lrPS2HiYVp8 What factors determine Earth’s climate: See IPCC-AR5 (2013-2014) tab on my web page: And this link from AR4 (2007) http://denverclimatestudygroup.com/?page_id=63 http://www.ipcc.ch/publications_and_data/ar4/wg1/en/faq-1-1.html

climate system - the inter-relationship and feedback of: Atmosphere Hydrosphere Biosphere Cryosphere Lithosphere (weathering reduces CO2; volcanism increases it)

@ 30oC +1oC = 8% increase in vapor 10oC = (50oF) 7.8 cc 20oC = (68oF) 15 cc 30oC = (86oF) 27.7 cc 40oC = (104oF) 49.8 cc

The Earth and its atmosphere The CO2 greenhouse gas effect is concentrated in the polar regions ! ! ! The most potent greenhouse gas is H2O - vapor The Earth and its atmosphere Particularly in the Arctic ! The large H2O greenhouse effect is controlled by temperature – H2O saturation doubles with every 10°C Increase As a result It is concentrated in the lower atmosphere of the tropics CO2 is evenly distributed throughout the atmosphere

WEEK 2

Earth’s past climate Earth’s deep past before the Cambrian (600 MaBP): hot and cold Earth’s past: Cambrian onward: mostly hot-house Earth;  100s parts per million (ppm) Climate trend in the Cenozoic – the last 65 million years; proxy data from 3600ppm to <200 ppm. More recent past: 180-280 part per million; how do we know – empirical data. Preview of next week’s field trip Today: 400 ppm and growing

Earth’s past climate Earth’s deep past and early atmosphere before the Cambrian (600 MaBP): hot and cold Earth self regulates 2.1 -2.3 Tim Lenton video – 9 minute overview Article Link: BBC Nature http://www.bbc.co.uk/nature/ancient_earth/Snowball_Earth You Tube – leaving for you to watch on your own: https://www.youtube.com/results?search_query=snow+ball+earth – various links

Earth’s past climate Earth’s deep past before the Cambrian (600 MaBP): hot and cold Earth’s past: Cambrian onward: mostly hot-house Earth;  100s parts per million (ppm) Climate trend in the Cenozoic – the last 65 million years; proxy data from 3600ppm to <200 ppm. More recent past: 180-280 part per million; how do we know – empirical data. Preview of next week’s field trip Today: 400 ppm and growing

Climate Changes from Ocean Sediment Cores, since 5 Ma Climate Changes from Ocean Sediment Cores, since 5 Ma. Milankovitch Cycles 41K 100 K 3.0Ma 4.0Ma 2.0Ma 1.0Ma 5.0Ma When CO2 levels get below ~400-600 ppm Orbital parameters become more important than CO2

Earth’s past climate Earth’s deep past before the Cambrian (600 MaBP): hot and cold Earth’s past: Cambrian onward: mostly hot-house Earth;  100s parts per million (ppm) Climate trend in the Cenozoic – the last 65 million years; proxy data from 3600ppm to <200 ppm. More recent past: 180-280 part per million; how do we know – empirical data. Preview of next week’s field trip Today: 400 ppm and growing

Scientific History of Climate change – PROXY DATA

Alternating Greenhouse Earth / Ice-house Earth Geologic cycles: Climate through the Phanerozoic: Carbon is the culprit Royer et al., 2003

Cenozoic Deep Sea Climate Record hyperthermals Azolla sequestering event Opening of the Drake passage isolating Antarctica and further drop in CO2 41k-100k & amplitude change: Increase in Antarctic ice Closing of Isthmus of Panama Zachos et al. 2008

Correlation of CO2 and temperature over last 65 million years Beerling and Royer, Nature 2011

Long-term Carbon Cycle: rocks Two generalized reactions… Photosynthesis/Respiration CO2 + H20 ↔ CH2O + O2 Weathering/Precipitation CO2 + CaSiO3 ↔ CaCO3 + SiO2

Long-term carbon cycle: rocks Berner, 2001

50 million years ago (50 MYA) Earth was ice-free. Atmospheric CO2 amount was of the order of 1000 ppm 50 MYA. Atmospheric CO2 imbalance due to plate tectonics ~ 10-4 ppm per year. 21

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Earth’s past climate Earth’s deep past before the Cambrian (600 MaBP): hot and cold Earth’s past: Cambrian onward: mostly hot-house Earth;  100s parts per million (ppm) Climate trend in the Cenozoic – the last 65 million years; proxy data from 3600ppm to <200 ppm. More recent past: 180-280 part per million; how do we know – empirical data. Preview of next week’s field trip Today: 400 ppm and growing

Climate Changes from Ocean Sediment Cores, since 5 Ma Climate Changes from Ocean Sediment Cores, since 5 Ma. Milankovitch Cycles 41K 100 K 3.0Ma 4.0Ma 2.0Ma 1.0Ma 5.0Ma When CO2 levels get below ~400-600 ppm Orbital parameters become more important than CO2

Earth’s past climate Earth’s deep past before the Cambrian (600 MaBP): hot and cold Earth’s past: Cambrian onward: mostly hot-house Earth;  100s parts per million (ppm) Climate trend in the Cenozoic – the last 65 million years; proxy data from 3600ppm to <200 ppm. More recent past: 180-280 part per million; how do we know – empirical data. Preview of next week’s field trip Today: 400 ppm and growing

- SO – WHAT CONTROLS CLIMATE

Gerhard et al., 2001

(latitudes & elevations) FEEDBACKS 2o Forcings Continents (latitudes & elevations) Ocean circulation weathering CO2 4o Forcings Volcanic eruptions Sunspots Cycles El Nino/ La Nina Cloud Solar storms 3o Forcings Obliquity Precession Eccentricity CO2 /CH4 1o Forcings Solar Luminosity Atm. Comp. FIRST ORDER: CONTINENTAL POSITIONS, LAND COVER, Rohling, et al., (PALAESENS Project mbrs), 2012

End of week 2 EXTRAS FOLLOW

Paleocene/Eocene Thermal Maximum PETM

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Proxy data: stable isotopes Complexities here relate to the onset of current ice-house stage. Continental configuration important – opening of the Drake Passage, closing of the Isthmus of Panama forcing the present North Atlantic conveyor belt. Gulf Stream – start of Northern Hemisphere glaciations. But let us also look at an astronomical driver – cycles in earth’s orbit Wikipedia

PETM - THE LAND RECORD

Bighorn Basin PETM interval in fluvial deposits with excellent alluvial paleosols - seen as color bands, which are soil horizons Found in Willwood Fm Reds, purples due to iron oxides in B horizons

Paleosol Density Pre-PETM PETM

Bighorn Basin Climate Plant fossils and isotopes show Mean Annual Temperature of 20o to 25o C or 68 to 77o F Similar to Gulf Coast region today

PROXY DATA-EXTRAS

FROM CSI TO GSI: GEOLOGICAL SAMPLE INVESTIGATION LET THE EVIDENCE SPEAK FOR ITSELF

WE CALL THIS EVIDENCE “PROXY” DATA

SOME OF THE EARLIEST PROXY DATA WAS FROM TERRESTRIAL DEPOSITS Strandlines/shorelines Moraines Till Kettle lakes, etc. We may know what caused these today, but imagine back then?

IT’S THE INTERPRETATION THAT’S NOT ALWAYS CORRECT Darwin observed ancient Alpine shorelines: interpreted as ocean shoreline Agassiz – later correctly interpreted as ice- dammed lake-shore strandlines/shoreline

Jean Louis R. Agassiz “Father” of Glaciology 1807-1873 Paleontologist Glaciologist

Photographic proxy data/evidence Ruddiman, 2008

EARLY PROXY DATA: TREE RINGS

Pollen & Lake core data Ruddiman, 2008

PROXY DATA: POLLEN DATA

PROXY DATA: LEAVES

Tree rings, corals, ice cores Ruddiman, 2008

PROXY DATA: ICE CORES

TERRESTRIAL DATA North American: Wisconsin Illinoian Kansan Nebraskan European: Wurm Riss Mindel Gunz

LATER EVIDENCE CAME FROM THE MARINE RECORD NOT WITHOUT IT’S PROBLEMS, BUT MORE COMPLETE

Cesare Emilani: Paleontologist, Chemist Father of Paleoceanography

Other Paleoceanographers Wally Broecker Thermal-haline “conveyor” belt of circulation

Other Paleoceanographers Bill Ruddiman Nick Shackleton

Other Paleoceanographers John Imbrie: CLIMAP

PROXY DATA: CORE DATA

PROXY DATA: BENTHIC FORAMS

PROXY DATA: PLANKTONIC FORAMS

Deep Sea Coring Ruddiman, 2008